3DS has a Game Boy/ Game Boy Color Virtual Console [update]

One of the 3DS's killer apps may be ... old games. As has been requested for the original DS and DSi since time immemorial (2004), Nintendo will offer downloadable Game Boy and Game Boy Color games on the 3DS, through a VIrtual Console-style store.

In addition, as shown at E3, Nintendo will offer 3D-ified versions of classics like Xevious.

Update: The transcript from Nintendo's conference last night show that Iwata specified games from the Game Boy and Game Boy Color -- not Advance. At least, not yet. We apologize for the confusion.